PIC12F510 datasheet(49/124 Pages) MICROCHIP

49 / 124 page

DS41268D-page 47

PIC12F510/16F506

7.1

Comparator Operation

A single comparator is shown in Figure 7-3 along with

the relationship between the analog input levels and

the digital output. When the analog input at VIN+ is less

than the analog input VIN-, the output of the comparator

is a digital low level. The shaded area of the output of

the comparator in Figure 7-3 represent the uncertainty

due to input offsets and response time. See Table 13-1

for Common Mode Voltage.

FIGURE 7-3:

SINGLE COMPARATOR

7.2

Comparator Reference

An internal reference signal may be used depending on

the comparator operating mode. The analog signal that

is present at VIN- is compared to the signal at VIN+, and

the digital output of the comparator is adjusted accord-

ingly (Figure 7-3). Please see Section 8.0 “Compara-

tor Voltage Reference Module (PIC16F506 only)” for

internal reference specifications.

7.3

Comparator Response Time

Response time is the minimum time after selecting a

new reference voltage or input source before the com-

parator output is to have a valid level. If the comparator

inputs are changed, a delay must be used to allow the

comparator to settle to its new state. Please see

Table 13-1

for

comparator

response

time

specifications.

7.4

Comparator Output

The comparator output is read through the CM1CON0

or CM2CON0 register. This bit is read-only. The

comparator output may also be used externally, see

Figure 7-3.

7.5

Comparator Wake-up Flag

The Comparator Wake-up Flag is set whenever all of

the following conditions are met:

•C1WU = 0 (CM1CON0<0>) or

C2WU = 0 (CM2CON0<0>)

• CM1CON0 or CM2CON0 has been read to latch

the last known state of the C1OUT and C2OUT bit

(MOVF CM1CON0, W)

• Device is in Sleep

• The output of a comparator has changed state

The wake-up flag may be cleared in software or by

another device Reset.

7.6

Comparator Operation During

Sleep

When the comparator is enabled it is active. To mini-

mize power consumption while in Sleep mode, turn off

the comparator before entering Sleep.

7.7

Effects of Reset

A Power-on Reset (POR) forces the CM2CON0

input pins to analog Reset mode. Device current is

minimized when analog inputs are present at Reset

time.

7.8

Analog Input Connection

Considerations

A simplified circuit for an analog input is shown in

Figure 7-4. Since the analog pins are connected to a

digital output, they have reverse biased diodes to VDD

and VSS. The analog input, therefore, must be between

VSS and VDD. If the input voltage deviates from this

range by more than 0.6V in either direction, one of the

diodes is forward biased and a latch-up may occur. A

maximum source impedance of 10 k

Ω is recom-

mended for the analog sources. Any external compo-

nent connected to an analog input pin, such as a

capacitor or a Zener diode, should have very little

leakage current.

–

VIN+

VIN-

Result

VIN-

VIN+

Note:

Analog levels on any pin that is defined as

a digital input may cause the input buffer to

consume more current than is specified.

PIC12F510 Datenblatt(PDF) 49 Page - Microchip Technology

PIC12F510 Datenblatt(HTML) 49 Page - Microchip Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 ...More

Datenblatt Download

Link URL